The Council of Ministers has two ways of taking decisions - unanimity, when everyone has to be in agreement - and qualified majority voting - a system of weighted votes.

QMV is the most common method of decision-making, used in all but the most sensitive issues.

Issues which are decided on by QMV are also voted on by the European Parliament. This means that the council and parliament act together in co-decision.

Under QMV, each member state is given a certain number of votes in the council, weighted according to its size and population. For example, Germany, the EU's largest state, has 10 votes, while Portugal has five and Finland three.

At present, there are 87 votes in the council, distributed between the 15 member states.

The qualified majority means that 62 votes are needed to pass a proposal, rather than the normal majority of 44.

The reason for the qualified majority, rather than a simple 50%, means that at least half the population of the EU and half the member states must be in favour of a motion to pass it.

But with enlargement, the balance between big and small countries will change.

If the distribution of votes remained the same, a group of small countries could in effect gang up against the big countries and vote them down, even though the small countries together represent fewer people than the big ones.

Some of the longest and hardest negotiations at the 2000 Nice summit were dedicated to working out how many votes each country should have in the future to avoid this situation.

The Nice Treaty allocates the 12 candidate countries their votes and adjusts the votes of the current member states.

Once all the countries have joined, there will be 345 votes in total.

To reach a qualified majority 255 votes will be required, as well as a majority of member states. As an added control, the votes cast will have to represent 62% of the EU population.